In internal combustion engines a high compression ratio has a positive effect upon efficiency of the internal combustion engine. Compression ratio is typically designated as a ratio of an entire cylinder volume before compression divided by a remaining cylinder volume after the compression. In internal combustion engines with external ignition in particular gasoline engines which have a fixed compression ratio, the compression ratio, however, must only be selected up to a level where a so called knocking of the internal combustion engine under full load operations is avoided. However, the compression ratio can be selected with higher values for the much more prevalent partial load operation of the internal combustion engine, thus with a low cylinder charge, without the knocking occurring. The important partial load operations of an internal combustion engine can be improved when the compression ratio is variably adjustable. In order to adjust the compression ratio systems with variable connecting rod length are known which actuate an eccentrical element adjustment arrangement of a connecting rod using hydraulic switch valves.
A connecting rod of this type is known for example from DE 10 2013 107 127 A1 and includes an eccentrical element adjustment arrangement for adjusting an effective connecting rod length, wherein the eccentrical element adjustment arrangement includes an eccentrical element that cooperates with an eccentrical element lever and two pistons that are respectively displaceably arranged in a respective hydraulic chamber and wherein eccentrical element rods engaging the eccentrical element lever are supported at the two pistons. An adjustment travel of the eccentrical element adjustment arrangement is adjustable by a switch valve. Adjusting the adjustment travel adjusts an effective connecting rod length. This controls the compression of the internal combustion engine. Check valves in the connecting rod respectively prevent any flow back of hydraulic fluid from the hydraulic chambers to a supply connection or a tank.
DE 10 2012 112 481 A1 discloses a hydraulic valve suitable for this purpose.